Stocks initially pared their losses after a better-than-expected factory orders report. New orders for factory goods climbed 0.7 percent in April, rising for a third-straight month and topping expectations for 0.5 percent.

"We've had some hesitation this morning but factory orders looked a bit better than expected and seemed to give a little more life into the market," said Todd Salamone, director of research at Schaeffer's Investment Research. "There's still a lot of data coming out later in the week—a lot of eyes are on the ECB."

Investors will be looking ahead to the monthly nonfarm payrolls report on Friday. Economists expect to see 218,000 jobs added in May and a 6.4 percent unemployment rate, according to a Reuters poll.

General Motors and Ford gained after both automakers reported sales that rose above estimates in May. Japanese rival Toyota also topped sales estimates.

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Tesla CEO Elon Musk said he plans to stay at least another 4 to 5 years as the chief of the electric car company, according to Dow Jones. Tesla is holding its annual shareholder meeting Tuesday.

"One area of the market that hasn't benefited from the asset value melt-up over the last several years has been commodities," said Jack Ablin, chief investment officer at BMO Private Bank. "While stock and bond markets continued to surge, the Dow Jones UBS Commodities Index has been losing ground since 2011...Notwithstanding the pullback, commodities now appear to be a more interesting asset class...While we do't expect a replay of the commodity bull run, we do believe that having a commodity allocation in a broadly diversified portfolio will enable investors to mitigate some of their other market risks."

In addition, President Barack Obama will begin his European trip with meetings in Poland to discuss security issues regarding Russia. Obama is also expected to meet with Ukrainian President-elect Petro Poroshenko.